OK, I think I have a better picture of how the handles were set in this door. I think I'm not the only one that pictured a pair of vertical handles with both holes relatively close to where the two panels would've met in the doorway. It seems these handles were set "towel bar" style (parallel to the short ends)? If I'm right here, I'm thinking this can at best be a bottom pane that can't be drilled. 5 inches on either end is a lot to compensate for/cover up but that's your call. I know I make lots of compromises (I call it getting creative) when I come across free stuff, but it's an aesthetics thing in the end. Regardless of what type of glass, you should be able to patch the holes in a snap. Any glass shop should be able to supply 3/8" square patches you can just silicone in place. The majority of glass shops don't work with 1/2", but a few do. I can't comment on how tempered vs hi-impact differ, but if you go the glass patch route, the guy at the glass shop should be able to give you a 3 sentence answer for free. As for carrying it vertically, the company a couple of stories above my office moved out a couple of years ago and I saw them carrying out the glass doors. What happened to the one they carried out horizontally was both funny and scary at the same time.